GigaBlox Nano Rev B replaces Rev A with two changes:
- Energy Efficient Ethernet (EEE) is disabled by default.
- An empty footprint has been added for an optional configuration EEPROM.
This applies to both versions:
- BB-GGN-A-1 → BB-GGN-B-1
- BB-GGN-A-1-NDAA → BB-GGN-B-1-NDAA
Here’s what those changes mean if you’re already using Rev A or designing around Rev B.
Is Rev B a drop-in replacement?
Yes. The mechanical and electrical interfaces remain unchanged:
- Same nominal 26 × 26 × 8 mm module dimensions.
- Same mounting arrangement.
- Same Samtec board-to-board connector and pinout.
- Same 5–60 VDC input range.
- Same four 10/100/1000 Mbps Ethernet ports.
- Same normal link-speed negotiation and packet forwarding.
You don’t need to redesign your carrier board or change the connector wiring. There is no software installation or programming step required before using Rev B.
Power consumption can differ when connected links are idle or lightly used, because Rev B no longer uses EEE. More on that below.
What is EEE?
Energy Efficient Ethernet, defined by IEEE 802.3az, is an optional power-saving feature.
When both ends of a link support and negotiate EEE, the Ethernet PHY can enter a Low Power Idle state during gaps in traffic. It wakes up again when data needs to be transmitted.
The link remains established. EEE doesn’t deliberately disconnect the link or renegotiate its speed each time it saves power.
It is mainly useful when a link is connected but spends a significant amount of time doing little. On heavily utilised links, the opportunity to save power is much smaller.
Why did we disable it?
EEE has some drawbacks:
- Waking from Low Power Idle adds a small amount of latency.
- Some Ethernet devices handle EEE poorly.
- In affected combinations of devices, this can contribute to intermittent links, reduced throughput or other connectivity problems.
We haven’t observed those issues specifically on GigaBlox Nano. We have encountered EEE-related problems on some of our other products, so disabling it on Nano was a precaution.
For our applications, we consider avoiding potential compatibility problems a worthwhile trade-off for a small increase in idle power consumption.
There is precedent for disabling EEE in industrial networking. For example, Beckhoff’s EtherCAT PHY selection guide requires it to be disabled. That requirement is specific to EtherCAT, rather than a general rule for all industrial Ethernet equipment.
Will Rev B still work with devices that support EEE?
Yes. EEE is optional.
An EEE-capable device connected to Rev B will establish a normal Ethernet link without activating EEE. A device that doesn’t support EEE continues operating normally.
Disabling EEE does not disable autonegotiation, force a lower link speed or reduce the switch’s forwarding throughput. It changes the link’s power-saving behaviour between periods of traffic.
How much does power consumption change?
We estimate a difference of around 0.6 W across four connected, lightly utilised ports compared with EEE-enabled operation.
That is an estimate for that operating condition, not a guaranteed maximum or a fixed increase in every installation.
The difference depends on the connected devices, negotiated speeds and traffic. If the connected devices weren’t using EEE in the first place, there is no EEE saving to lose. On heavily utilised links, the difference is much smaller.
Rev B should therefore not be treated as consuming an additional 0.6 W in every situation. Idle consumption and consumption under sustained traffic are different operating conditions.
How is EEE disabled? Can it be re-enabled?
EEE is disabled through a hardware pin strap on the switch IC. It is not disabled by an EEPROM image or customer-loaded firmware.
Changing that default requires a board-level hardware modification rather than a software setting exposed to the user. If your application requires EEE, contact us with your board revision and requirements before modifying the board.
What is the EEPROM footprint for?
Rev B adds an EEPROM footprint, but no EEPROM is fitted to the standard board.
The footprint allows a configuration EEPROM to be added for custom switch settings, such as enabling jumbo frames. Adding the footprint does not mean those features are enabled by default.
For normal use:
- There is no EEPROM to program.
- You don’t need to supply a configuration file.
- The board operates using its factory hardware configuration.
- The EEE setting does not depend on an EEPROM.
If an EEPROM is fitted for a custom configuration, its contents matter. An incorrectly programmed EEPROM should not be assumed to behave like an absent EEPROM.
When did the revision change happen?
Rev B was released on March 15, 2026. BB-GGN-B-1-NDAA began shipping on June 1, 2026. Rev A is no longer available to purchase.
Use the full manufacturer part number, including the revision and NDAA suffix where applicable, when specifying the product on an order.
Further reading: